diff --git a/HISTORY.txt b/HISTORY.txt
index ea41f71..d6392f0 100644
--- a/HISTORY.txt
+++ b/HISTORY.txt
@@ -174,6 +174,8 @@ Genesis Plus GX 1.7.5 (xx/xx/xxxx) (Eke-Eke)
   (HOME + MINUS with Wii controllers or R TRIGGER + START with Gamecube controller)
 * added 50hz progressive mode (576p) support for emulation
 * added WiiU GamePad Controller support on vWii (Fix94)
+* added support for Sega CD / Mega-CD PRG-RAM and Word-RAM cheat codes
+* added configurable overclock setting for M68K, S68K and Z80 CPUs
 * reduced SRAM files size
 * improved A/V Sync: when VSYNC is enabled, audio resampler output rate is now adjusted (+/-0,1 %)
   to always keep audio & video synchronized and input lag is reduced by one frame.
diff --git a/Makefile.gc b/Makefile.gc
index e93244f..9650172 100644
--- a/Makefile.gc
+++ b/Makefile.gc
@@ -26,7 +26,7 @@ INCLUDES	:=	core core/m68k core/z80 core/sound core/tremor core/ntsc core/input_
 # options for code generation
 #---------------------------------------------------------------------------------
 
-CFLAGS  = -O3 -fomit-frame-pointer -Wall -Wno-strict-aliasing $(MACHDEP) $(INCLUDE) -DUSE_LIBTREMOR -DDISABLE_MANY_OGG_OPEN_FILES -DUSE_16BPP_RENDERING -DALT_RENDERER -DBLIP_INVERT
+CFLAGS  = -O3 -fomit-frame-pointer -Wall -Wno-strict-aliasing $(MACHDEP) $(INCLUDE) -DUSE_LIBTREMOR -DDISABLE_MANY_OGG_OPEN_FILES -DUSE_16BPP_RENDERING -DALT_RENDERER -DBLIP_INVERT -DM68K_OVERCLOCK_SHIFT=20 -DZ80_OVERCLOCK_SHIFT=20
 CXXFLAGS	=	$(CFLAGS)
 
 LDFLAGS	=	$(MACHDEP) -Wl,-Map,$(notdir $@).map
diff --git a/Makefile.wii b/Makefile.wii
index 66af42f..45feb1c 100644
--- a/Makefile.wii
+++ b/Makefile.wii
@@ -30,7 +30,7 @@ INCLUDES	:=	core core/m68k core/z80 core/sound core/tremor core/ntsc core/input_
 # options for code generation
 #---------------------------------------------------------------------------------
 
-CFLAGS  = -O3 -fomit-frame-pointer -Wall -Wno-strict-aliasing $(MACHDEP) $(INCLUDE) -DMAXROMSIZE=15728640 -DUSE_LIBTREMOR -DUSE_LIBCHDR -DUSE_16BPP_RENDERING -DALT_RENDERER -DBLIP_INVERT -DHW_RVL -DCPU_IS_BIG_ENDIAN=1 -DWORDS_BIGENDIAN=1 -DPACKAGE_VERSION=\"1.3.2\" -DFLAC_API_EXPORTS -DFLAC__HAS_OGG=0 -DHAVE_LROUND -DHAVE_STDINT_H  -DHAVE_SYS_PARAM_H -D_7ZIP_ST
+CFLAGS  = -O3 -fomit-frame-pointer -Wall -Wno-strict-aliasing $(MACHDEP) $(INCLUDE) -DMAXROMSIZE=15728640 -DUSE_LIBTREMOR -DUSE_LIBCHDR -DUSE_16BPP_RENDERING -DALT_RENDERER -DBLIP_INVERT -DHW_RVL -DCPU_IS_BIG_ENDIAN=1 -DWORDS_BIGENDIAN=1 -DPACKAGE_VERSION=\"1.3.2\" -DFLAC_API_EXPORTS -DFLAC__HAS_OGG=0 -DHAVE_LROUND -DHAVE_STDINT_H  -DHAVE_SYS_PARAM_H -D_7ZIP_ST -DM68K_OVERCLOCK_SHIFT=20 -DZ80_OVERCLOCK_SHIFT=20
 CXXFLAGS	=	$(CFLAGS)
 
 LDFLAGS	=	$(MACHDEP) -Wl,-Map,$(notdir $@).map
diff --git a/builds/genplus_cube.dol b/builds/genplus_cube.dol
index 5cdf633..2841d34 100644
Binary files a/builds/genplus_cube.dol and b/builds/genplus_cube.dol differ
diff --git a/builds/genplus_wii.dol b/builds/genplus_wii.dol
index 1e0fb8d..49f5d06 100644
Binary files a/builds/genplus_wii.dol and b/builds/genplus_wii.dol differ
diff --git a/gx/config.c b/gx/config.c
index 9364d8a..b857f4e 100644
--- a/gx/config.c
+++ b/gx/config.c
@@ -127,6 +127,9 @@ void config_default(void)
   config.add_on         = HW_ADDON_AUTO;
   config.hot_swap       = 0;
   config.cd_latency     = 1;
+  config.m68k_overclock = 1.0;
+  config.s68k_overclock = 1.0;
+  config.z80_overclock  = 1.0;
 
   /* video options */
   config.xshift   = 0;
diff --git a/gx/config.h b/gx/config.h
index a1c1be5..9107b61 100644
--- a/gx/config.h
+++ b/gx/config.h
@@ -126,6 +126,9 @@ typedef struct
   float ntsc_artifacts;
   float ntsc_fringing;
   float ntsc_bleed;
+  float m68k_overclock;
+  float s68k_overclock;
+  float z80_overclock;
   char sys_rom[12][256];
 } t_config;
 
diff --git a/gx/docs/README.doc b/gx/docs/README.doc
index dc9edcc..3c7df87 100644
Binary files a/gx/docs/README.doc and b/gx/docs/README.doc differ
diff --git a/gx/docs/README.pdf b/gx/docs/README.pdf
index 7602f17..4379dfb 100644
Binary files a/gx/docs/README.pdf and b/gx/docs/README.pdf differ
diff --git a/gx/gui/menu.c b/gx/gui/menu.c
index a88b704..8118735 100644
--- a/gx/gui/menu.c
+++ b/gx/gui/menu.c
@@ -392,6 +392,9 @@ static gui_item items_system[] =
   {NULL,NULL,"Lock-On: SONIC&KNUCKLES",    "Select Lock-On cartridge type",               56,132,276,48},
   {NULL,NULL,"Cartridge Swap: OFF",        "Enable/Disable cartridge hot swap",           56,132,276,48},
   {NULL,NULL,"BIOS & Lock-On ROM paths",   "Configure Boot ROM & Lock-On ROM paths",      56,132,276,48},
+  {NULL,NULL,"Main 68k Overclock: 3.0x",   "Adjust Mega Drive /Genesis CPU clock speed",  56,132,276,48},
+  {NULL,NULL,"Sub 68k Overclock: 3.0x",    "Adjust Sega CD / Mega-CD CPU clock speed",    56,132,276,48},
+  {NULL,NULL,"Z80 Overclock: 3.0x",        "Adjust Z80 CPU clock speed",                  56,132,276,48},
   {NULL,NULL,"SVP Cycles: 1500",           "Adjust SVP chip emulation speed",             56,132,276,48}
 };
 
@@ -1356,14 +1359,29 @@ static void systemmenu ()
 
   sprintf (items[10].text, "Cartridge Swap: %s", (config.hot_swap & 1) ? "ON":"OFF");
 
+  if (config.m68k_overclock > 1.0)
+    sprintf (items[12].text, "Main 68k Overclock: %1.1fx", config.m68k_overclock);
+  else
+    sprintf (items[12].text, "Main 68k Overclock: OFF");
+
+  if (config.s68k_overclock > 1.0)
+    sprintf (items[13].text, "Sub 68k Overclock: %1.1fx", config.s68k_overclock);
+  else
+    sprintf (items[13].text, "Sub 68k Overclock: OFF");
+
+  if (config.z80_overclock > 1.0)
+    sprintf (items[14].text, "Z80 Overclock: %1.1fx", config.z80_overclock);
+  else
+    sprintf (items[14].text, "Z80 Overclock: OFF");
+
   if (svp)
   {
-    sprintf (items[12].text, "SVP Cycles: %d", SVP_cycles);
-    m->max_items = 13;
+    sprintf (items[15].text, "SVP Cycles: %d", SVP_cycles);
+    m->max_items = 16;
   }
   else
   {
-    m->max_items = 12;
+    m->max_items = 15;
   }
 
   GUI_InitMenu(m);
@@ -1634,10 +1652,40 @@ static void systemmenu ()
         break;
       }
 
-      case 12:  /*** SVP cycles per line ***/
+      case 12:  /*** Main 68k Overclock ***/
+      {
+        GUI_OptionBox(m,0,"Main 68k Overclock Ratio",(void *)&config.m68k_overclock,0.1,1.0,3.0,0);
+        if (config.m68k_overclock > 1.0)
+          sprintf (items[12].text, "Main 68k Overclock: %1.1fx", config.m68k_overclock);
+        else
+          sprintf (items[12].text, "Main 68k Overclock: OFF");
+        break;
+      }
+
+      case 13:  /*** Sub 68k Overclock ***/
+      {
+        GUI_OptionBox(m,0,"Sub 68k Overclock Ratio",(void *)&config.s68k_overclock,0.1,1.0,3.0,0);
+        if (config.s68k_overclock > 1.0)
+          sprintf (items[13].text, "Sub 68k Overclock: %1.1fx", config.s68k_overclock);
+        else
+          sprintf (items[13].text, "Sub 68k Overclock: OFF");
+        break;
+      }
+
+      case 14:  /*** Z80 Overclock ***/
+      {
+        GUI_OptionBox(m,0,"Z80 Overclock Ratio",(void *)&config.z80_overclock,0.1,1.0,3.0,0);
+        if (config.z80_overclock > 1.0)
+          sprintf (items[14].text, "Z80 Overclock: %1.1fx", config.z80_overclock);
+        else
+          sprintf (items[14].text, "Z80 Overclock: OFF");
+        break;
+      }
+
+      case 15:  /*** SVP cycles per line ***/
       {
         GUI_OptionBox(m,0,"SVP Cycles",(void *)&SVP_cycles,1,1,1500,1);
-        sprintf (items[12].text, "SVP Cycles: %d", SVP_cycles);
+        sprintf (items[15].text, "SVP Cycles: %d", SVP_cycles);
         break;
       }
 
@@ -1707,6 +1755,11 @@ static void systemmenu ()
     }
   }
 
+  /* Initialize CPU overclock ratio */
+  m68k.cycle_ratio = (100 << M68K_OVERCLOCK_SHIFT) / (int)(config.m68k_overclock * 100.0);
+  s68k.cycle_ratio = (100 << M68K_OVERCLOCK_SHIFT) / (int)(config.s68k_overclock * 100.0);
+  z80_cycle_ratio  = (100 << Z80_OVERCLOCK_SHIFT) / (int)(config.z80_overclock * 100.0);
+
   GUI_DeleteMenu(m);
 }
 
@@ -2034,27 +2087,27 @@ static void videomenu ()
       }
 
       case VI_OFFSET+2: /*** NTSC Sharpness ***/
-        GUI_OptionBox(m,update_bgm,"NTSC Sharpness",(void *)&config.ntsc_sharpness,0.01,-1.0,1.0,0);
+        GUI_OptionBox(m,0,"NTSC Sharpness",(void *)&config.ntsc_sharpness,0.01,-1.0,1.0,0);
         sprintf(items[VI_OFFSET+2].text, "NTSC Sharpness: %1.2f", config.ntsc_sharpness);
         break;
 
       case VI_OFFSET+3: /*** NTSC Resolution ***/
-        GUI_OptionBox(m,update_bgm,"NTSC Resolution",(void *)&config.ntsc_resolution,0.01,0.0,1.0,0);
+        GUI_OptionBox(m,0,"NTSC Resolution",(void *)&config.ntsc_resolution,0.01,0.0,1.0,0);
         sprintf(items[VI_OFFSET+3].text, "NTSC Resolution: %1.2f", config.ntsc_resolution);
         break;
 
       case VI_OFFSET+4: /*** NTSC Artifacts ***/
-        GUI_OptionBox(m,update_bgm,"NTSC Artifacts",(void *)&config.ntsc_artifacts,0.01,-1.0,0.0,0);
+        GUI_OptionBox(m,0,"NTSC Artifacts",(void *)&config.ntsc_artifacts,0.01,-1.0,0.0,0);
         sprintf(items[VI_OFFSET+4].text, "NTSC Artifacts: %1.2f", config.ntsc_artifacts);
         break;
 
       case VI_OFFSET+5: /*** NTSC Color Bleed ***/
-        GUI_OptionBox(m,update_bgm,"NTSC Color Bleed",(void *)&config.ntsc_bleed,0.01,-1.0,1.0,0);
+        GUI_OptionBox(m,0,"NTSC Color Bleed",(void *)&config.ntsc_bleed,0.01,-1.0,1.0,0);
         sprintf(items[VI_OFFSET+5].text, "NTSC Color Bleed: %1.2f", config.ntsc_bleed);
         break;
 
       case VI_OFFSET+6: /*** NTSC Color Fringing ***/
-        GUI_OptionBox(m,update_bgm,"NTSC Color Fringing",(void *)&config.ntsc_fringing,0.01,-1.0,1.0,0);
+        GUI_OptionBox(m,0,"NTSC Color Fringing",(void *)&config.ntsc_fringing,0.01,-1.0,1.0,0);
         sprintf(items[VI_OFFSET+6].text, "NTSC Color Fringing: %1.2f", config.ntsc_fringing);
         break;
 
diff --git a/gx/main.c b/gx/main.c
index 9f94d6d..352285d 100644
--- a/gx/main.c
+++ b/gx/main.c
@@ -3,7 +3,7 @@
  *
  *  Genesis Plus GX
  *
- *  Copyright Eke-Eke (2007-2021), based on original work from Softdev (2006)
+ *  Copyright Eke-Eke (2007-2022), based on original work from Softdev (2006)
  *
  *  Redistribution and use of this code or any derivative works are permitted
  *  provided that the following conditions are met:
@@ -282,6 +282,11 @@ void reloadrom(void)
     config.hot_swap |= 2;
   }
 
+  /* Initialize CPU overclock ratio */
+  m68k.cycle_ratio = (100 << M68K_OVERCLOCK_SHIFT) / (int)(config.m68k_overclock * 100.0);
+  s68k.cycle_ratio = (100 << M68K_OVERCLOCK_SHIFT) / (int)(config.s68k_overclock * 100.0);
+  z80_cycle_ratio  = (100 << Z80_OVERCLOCK_SHIFT) / (int)(config.z80_overclock * 100.0);
+
   /* Auto-Load Backup RAM */
   slot_autoload(0,config.s_device);